c - 根据用户输入查找插值

Question

我对算法做了一些修改，并在函数中获取了一个值(虽然不正确)，但返回值拒绝将其发送回主函数。另外，我无法得到要求程序重新运行以发挥作用的代码部分。

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <float.h>
/*Prototype for functions used*/
float getdistance(float[], float[], float, int);
float printvalue(float);

int main()
{

      int maxtime = 18;
      float usertime = 0;
      char reiteration;
      char y, n;
      int reit_choice = 0;
      float interpolation = 0.0;
      float time_arr[]={0,3,5,8,10,12,15,18};
      float distance_arr[]={2,5.2,6,10,10.4,13.4,14.8,18};
      do
      { 
       printf("Please enter a number between 0 and 18 for the starting time:");
       scanf("%f", &usertime, "\b");
        while(usertime <0 || usertime >18)
       {
          printf("The value you have entered is not valid, please enter a value between 1 and 18");
          scanf("%f", &usertime, "\b");
       }/*End of data verification loop*/
       getdistance(time_arr, distance_arr, usertime, maxtime);
       printf("%f", interpolation);
       printvalue(interpolation);

       system("pause");

       printf("would you like to check another time?(y/n)");
       scanf("%c[y n]", &reiteration, "\b");
       while(reiteration!='y' || reiteration!='n')
       {
          printf("Please enter either y for yes or n for no");
          scanf("%c", &reiteration, "\b");
       }/*End of choice verification loop*/
       if(reiteration = 'y')
       {
         reit_choice = 1;
       }
       else
       {
         reit_choice = 0;
       }
}/*End of do loop*/
while(reit_choice);

}/*End of main loop*/

float getdistance(float time_arr[], float distance_arr[], float usertime, int maxtime)
{
   int index=0;
   float interpolation = 0;

   for(index; usertime > time_arr[index]; index++)
   {
      if(usertime<3)
      {
         break;
      }
   }/*End of value assignment for loop*/
   interpolation = (time_arr[index]) + (((time_arr[index +1] -     time_arr[index])/(distance_arr[index +1] - distance_arr[index])) * (usertime - distance_arr[index]));
   printf("%f", interpolation);
   return interpolation;
}/*End of distance calculation loop*/

float printvalue(float interpolation)
{
   printf("The interpolation was %f", interpolation);
}/*End of screen print loop*/

Answer 1

输出0的原因是

getdistance(time_arr, distance_arr, usertime, maxtime);

在int main()函数中，您调用函数getdistance来计算插值值并返回该值，但在main函数中返回值没有分配给变量插值。所以你必须将代码修改为

interpolation = getdistance(time_arr, distance_arr, usertime, maxtime);
printvalue(interpolation);

这将打印输出